car not holding boost?

gooner8

gooner8

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car seems to be playing up! When on full boost it keep holding back and banging? Thinking maybe spark plug gaps? Want is the gap for an evo 4? Thanks
 
Dirtmatt

Dirtmatt

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Plugs of leads would be a good place to start, if they are failing will cause it to miss on full boost..

Unless its over boosting? Fuel cut does the same thing
 
gooner8

gooner8

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wouldn't say over boosting under if anything! Was mapped to 1.3 bar and it hit that and drop's .1 .2 of a bar and bangs like launch control but at 60 mph? Cheers for the reply's any one know the gap size? :)
 
B6lee

B6lee

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0.7mm should do you :)
But to be honest I'd be looking for possible split or loose vaccine pipe if it's happened all of a sudden
 
gooner8

gooner8

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0.7mm should do you :)
But to be honest I'd be looking for possible split or loose vaccine pipe if it's happened all of a sudden

yeah i did think that mate slit or a chauf but cant see anything? Where would be good to look if your thinking of anywhere? Maybe i'll have to look under it some how, cant see anything from the top! Cheers:)
 
RsvRob

RsvRob

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Gap to 0.55
If it's on full boost and above 60mph I'd say plugs or packs.
Had someone mapped to 1.8. He changed plugs on service and got the same, pops bangs on full boost. He'd forgot to gap correctly and wasnt getting full spark
 
gooner8

gooner8

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sorry been busy what i wanted to say is, i went out last night the temp was down by 10 c @ 19 and it seemed ok?? Could it be the heat? Cheers :)
 
gooner8

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will whip them out tomor and have a look. Hopefully be a nice easy fix? :)
 
gooner8

gooner8

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want size are the spark plugs? 17 mm? Do i do 0.7 mm grab or 0.5.5 mm? Thanks :)
 
Last edited:
gooner8

gooner8

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what's cop and? Took them out 3 were at 0.7 and one at 0.6, set them all the same went for a drive and it seem's ok, will turn the boost back up after the gp and test again. Thanks :)
 
And@fcm

And@fcm

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Yeah cop ment coil on plug. 0.7is too big really for standard packs. What did you gap them too
 
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